1. Field of the Invention
The present invention relates to biochemical methods of detecting and/or classifying the species and/or strain of an alga and detecting the presence of toxins of algal origin.
2. Description of the Related Art
Contamination of shellfish with toxins produced by aquatic organisms is an on-going problem with the shellfish industry and aquaculture worldwide. Bans on the sale and consumption of shellfish from discrete coastline regions are often provoked by toxic harmful algal blooms (HABs). HABs are harmful to both human consumers and the ecosystem as a whole, as toxins produced by algae can sicken and kill many forms of aquatic organisms. Further, contamination of shellfish with algal toxins can occur in the absence of observed HABs. Hence the need for continuous surveillance programs to protect the public from food-borne illness due to contaminated shellfish.
Consumption of shellfish contaminated with algal toxin can lead to paralytic shellfish poisoning (PSP), a serious and potentially fatal illness. There are several types of PSP toxins (PST): saxitoxin (STX), neosaxitoxin (NEO), gonyautoxins 2 and 3 (GTX2,3), gonyautoxins 1 and 4 (GTX1,4), decarbamoyl saxitoxin (dcSTX), B-1 (GTX5), C-1 and C-2 (C1,2), C-3 and C-4 (C3,4) and B-2 (GTX6) toxin [1]. STX, one of the more common ones, causes paralytic symptoms in an organism by acting as a potent sodium channel blocker [2]. PST are poisonous to organisms higher up the food chain [3] due to the accumulation in bivalves of a range of neurotoxins produced by several dinoflagellates, particularly those of the genera Alexandrium, Gymnodinium and Pyrodinium. 
Rapid and reliable species identification is a requirement for both scientific research into HABs and commercial monitoring programs for the shellfish industry. In general algae research, morphological criteria are sufficient to classify unicellular algae to species, and to identify potentially toxin-producing dinoflagellates. Difficulties arise, however, if morphological characteristics that distinguish one alga from the rest of the plankton community are lacking. For instance, some morphospecies have proven to be consistently linked to toxicity [e.g., A. catenella (Whedon et Kofoid) has been found to be constantly toxic], but other morphospecies such as A. tamarense (Lebour) and Balech Talyor are known to exist in both toxic and non-toxic strains [4]. Even with considerable time and effort, morphospecies (which exist in both toxic and non-toxic strains) might not be able to be differentiated by traditional microscopy since they may have identical morphology. To remedy these problems, identification methods that use molecular probes for nucleic acids or species-specific antibodies to detect specific toxin-producing algae strains have been developed [5,6]. However these approaches suffer from cross-reactivity between species and strains, as well as the diversity of algae species, strains and their toxins.
The study and identification of PSTs in the laboratory has been performed using a variety of biological, biochemical and chemical analytical procedures. Among them, biochemical (ELISA, receptor binding), tissue culture bioassays [7], mouse bioassays [8] or sophisticated chemical analytical alternatives (HPLC-FD [9] and LC-MS [10], etc) for routine toxin monitoring. They are configured to yield extremely high sensitivity and specificity towards the target toxin analyte. However, limited availability of pure toxins commercially and the large variation in specificity of the antibody to individual toxins hampered their application.
There exists a need for new methods of identifying species and strains of algae and detecting the presence or absence of algal toxins.